3D semiconductor devices and structures with at least two single-crystal layers

A 3D semiconductor device, the device including: a first level including a first single crystal layer, the first level including first transistors, where the first transistors each include a single crystal channel; first metal layers interconnecting at least the first transistors; and a second level including a second single crystal layer, the second level including second transistors, where the second level overlays the first level, where the second level is bonded to the first level, where the bonded includes oxide to oxide bonds, where the second transistors each include at least two side-gates, and where through the first metal layers power is provided to at least one of the second transistors.